Lubricating composition



Patented July 24, 1951 LUBRICATING COMPOSITION Denham Harman and George L. Perry, Berkeley, Calif., assignors to Shell Development Company, San Francisco, Calif., a corporation of Delaware No Drawing. Application October 28, 1946, Serial No. 706,085

7 Claims.

This invention relates to lubricating compositions, and more particularly to extreme pressure lubricants and to novel extreme pressure agents, as well as their preparation.

The function and requirements of extreme pressure additives for mineral oils have been the subjects of a large volume of literature, both in regard to the use of such additives in hypoid gear operation and in cutting oils, as well as for other uses. The patent art is replete with such disclosures. Some of these additives are more or less effective. For example, various types of sulfurized products are known, such as sulfurized mineral oil, various thiocarbonates, etc. In sulfurizing a saturated organic compound, the latter may act as a solvent for the sulfur, little or no reaction taking place. Alternatively, the compound may lose hydrogen, thus becoming unsaturated, following which sulfur may add to an unsaturated carbon atom. The use of such products has been confined principally to mineral oil lubricants.

It is an object of the present invention to provide a novel method for the preparation of extreme pressure lubricants and lubricant additives. It is another object of this invention to provide novel lubricants and lubricating compositions, comprising either mineral oil base lubricants, or compositions of entirely synthetic origin. Other and further objects of the present invention will appear in the course of the following description.

Now, in accordance with this invention it has been found that highly effective extreme pressure agents may be produced by the reaction of sulfur with sulfur containing organic compounds having units of the general formula wherein m, n, p and r are integers and each R is an organic radical, especially an aliphatic hydrocarbon radical. The structure of the products of the present invention has not been determined.

The lubricants and lubricant additives of the present invention may be prepared by use of any form of elemental sulfur, such as flowers of sulfur,

colloidal sulfur, lac sulfur, sublimed sulfur, precipitated sulfur, washed sulfur, etc.

Elemental sulfur, such as the forms given above, is heated with organic sulfur-containing compounds, especially compounds'such as mercaptans, sulfides, disulfides, or polysulfides, either of monomeric or polymeric character. These include monomers having the general structures Rr-SH, RSR, RSS-H, R-SS-R,

HO-R-S-ROH, etc., wherein p is an integer and each R is an organic radical, especially an aliphatic hydrocarbon radical.

Mercaptans with which sulfur reacts directly to form lubricants and/or lubricant additives include those having the general formula wherein R is a hydrocarbon radical, preferably a saturated aliphatic hydrocarbon radical. Typical mercaptans suitable for this purpose are for example, propyl mercaptan, isopropyl mercaptan, normal-butyl mercaptan, sec-butyl mercaptan, tert-butyl mercaptan, n-amyl mercaptan, l-methylbutyl mercaptan, :Z-methylbutyl mercaptan, S-methyl butyl mercaptan, 1,1-dimethylpropyl mercaptan, 1,2-dimethylpropyl mercaptan, 2,3-dimethylpropyl mercaptan, 1,3 -dimethylpropyl mercaptan, n-hexyl mercaptan, l-ethylbutyl mercaptan, 2-ethylbutyl mercaptan, 3- ethylbutyl mercaptan, n-heptyl mercaptan, noctyl mercaptan, n-nonyl mercaptan, n-decyl mercaptan, n-dodecyl mercaptan, Z-ethylhexyl mercaptan, S-ethylhexyl mercaptan, 4-ethylhexy1 mercaptan, 2-propylhexyl mercaptan, 3-propylheptyl mercaptan, 3-isopropylocty1 mercaptan, and their homologs and analogs.

Another type of mercaptan which may be used in the preparation of the lubricants herein described have the general formula wherein X is a substituent such as a hydrogen atom, hydrocarbon group or acyl radical, and R is a hydrocarbon radical. These include mercapto alcohols such as mercaptoethyl alcohol, mercaptopropyl alcohol, mercaptobutyl alcohol, mercaptoamyl alcohol, mercaptohexyl alcohol, mercaptoheptyl alcohol, mercaptooctyl alcohol, mercaptononyl alcohol, mercaptodecyl, mercaptododecyl, etc., wherein the sulfhydryl and hydroxyl groups are at opposite ends of the hydrocarbon chain.

Although such a configuration is preferred for the preparation of the present lubricants, alternative configurations include those in which the hydrocarbon is highly branched and/or in which wherein R4 and R are like or different hydrocarbon, particularly alkyl, radicals. Preferably, the mercapto group and the ether radical --O'-R5 are attached to opposite terminal carbon atoms of a saturated hydrocarbon. These include such ethers as l-mercapto-4-methoxybutane, l-mercapto-S-ethoxypentane, 1 mercapto-4-ethoxybutane, 1-mercapto-S-methoxyhexane, l-mercapto 6 ethoxyhexane, l-mercapto-fi-propoxyhexane, etc. Such ethers may have branched hydrocarbon radicals. For example, suitable ethers of this type are 1-mercapto-2-ethyl-3-methoxypropane, 1-mercapto-3-methyl-4-ethoxybutane, l-mercapto-3-isopropyl-7-butoxyheptane, etc.

Other ethers which may be used to form satisfactory lubricants include those in which the mercapto group and/or the alkoxy group are attached to carbon atoms other than terminal carbon atoms. These are illustrated by such ethers as l-mercapto- 2 -methoxypropane, 1-mercapto-3- .-ethoxybutane, 1 mercapto 4 propoxyhexane,

l-mercapto 5 butoxydecane, 2 mercapto-3- methoxy-propane, 3-mercapto- 4 -'ethoxybutane,

4-mercapto 5 propoxypentane, 2-mercapto-3- methoxybutane, 3-mercapto 5 ethoxyhexane, 2-mercapto-3-ethyl-4-methoxypentane, etc.

Esters of mercapto alcohols likewise may be used for the formation of the lubricants described .herein. These have the general formula where in Re and R7 are hydrocarbon radicals. Preferred esters having the above configuration include those in which the mercapto group and the ester group are attached to terminal carbon atoms of a linear hydrocarbon. The esters from which the most satisfactory lubricants are prepared are those in which R7 is a saturated aliphatic hydrocarbon radical having less than 13 carbon atoms. These include such esters as l-mercapto-3-methoyloxypropane, 1-mercapto-4- ethoxyloxybutane, 1 mercapto-5-butoyloxypentane, l-mercapto- 6 -(2-ethylhexoyloxy) hexane and their homologs and analogs.

The esters may have other configurations, such as the sufhydryl group, the ester groups or an alkyl group being attached to carbon atoms which are not terminals of a hydrocarbon chain. Typical esters having such configurations are l-mercapto-2-methoyloxypropane, 1-mercapto-4-ethoyloxyhexane, 2-mercapto-3-propoyloxypropane, l-mercapto-5-ethoyloxypentane, 2-mercapto-3- methoyloxybutane, 2-mercapto- 5 -methoyloxyhexane, 1-mercapto-2-methyl-3-methoyloxypropane, etc.

Organic sulfides which may be reacted with sulfur according to the process of the present invention have the general configuration wherein R1 and R2 are organic radicals, especially alkyl, hydroxyalkyl, carboxyalkyl or alkoxyl radicals. These include sulfides having similar or dissimilar radicals, and mixtures of such groups of sulfides as well as individual members thereof. Satisfactory starting materials, of these types, for the preparation of reaction products with sulfur, include dialkyl sulfides such as bis(tertiary-butyl) sulfide, diamyl sulfides, bis(2-ethylhexyl) sulfide, methyl ethyl sulfide, n-propyl tertiary-butyl sulfide, etc.

Bis(hydroxyalkyl) sulfides from which the present lubricants may be prepared include bis(2-hydroxyethyl) sulfide, bis(3-hydroxypropyl) sulfide, bis(l-hydroxybutyl) sulfide, 'bis(5- hydroxyamyl) sulfide, (Z-hydroxyethyl) (3-hydroxypropyl) sulfide, and their homologs and analogs.

Ethers of bis(hydroxyalkyl) sulfides which may be reacted with sulfur as described hereinafter are exemplified by bis(2-methoxyethyl) sulfide, bis(ethoxypropyl) sulfide, bis(ethoxybutyl) sulfide, bis[2 (2 ethylhexoxy)propyll sulfide, 2-methoxyethyl-3-ethoxypropyl sulfide, etc. Of this group, the sulfides containing a z-ethylhexoyl radical give reaction products with sulfur which have superior lubricating properties.

Esters of bis(hydroxyalkyl) sulfides which react with sulfur for lubricants are, for example, bis(methoyloxymethyl) sulfide, bisl2-(2-ethylhexoyloxy) ethyl] sulfide, bis [3-(2-ethylhexoyl- .oxy) propyl] sulfide, etc.

Disulfides and polysulfides (having structures similar to those of the above-mentioned mercaptans and sulfides except that the sulfur linkage in the latter compounds is replaced with a disulfide or polysulfide linkage) may be reacted with sulfur as described hereinbelow to form lubricants and lubricant additives.

The sulfur compounds described above have at least one unit of the general formula -[R-(S)p]r-- where in R is an organic radical, p is an integer and 1' is 1, various end groups such as hydrogen wherein r is an integer greater than 1 and R is a hydrocarbon radical. Other polymers which may be reacted with sulfur include those of his (hydroxyalkyl) sulfides, disulfides and polysulfides, having the general formula wherein p is an integer, r is an integer greater than 1, and each R is a hydrocarbon radical.

Another group of polymers which form particularly effective reaction products with sulfur are the adducts of hydrogen sulfide or mercaptans with olefinic materials, especially ethers having at least one unsaturated linkage in each radical attached to the ether oxygen atom. Such adducts include those of hydrogen sulfide with diallyl ether or divinyl ether. Polymers of the latter type have the general formula wherein each R. is a saturated hydrocarbon radical, R1 and R2 are terminal radicals of the group consisting of mercaptoalkyl or alkenyl radicals, and n is an integer. Polyethers of the above type are described in a copending' application, Serial No. 701,412, filed October 5, 1946, now Patent Number 2,522,512, issued September 19, 1950, and in application, Serial No. 708,194, filed November 6, 1946, now abandoned. Furthermore, polymers of the above types may be reacted with sulfur either before or after modification of terminal groups, such as by etherification, esterification, etc.

As stated hereinbefore, the present lubricants and lubricant additives are prepared by reacting sulfur with any one or a mixture of the above types of organic sulfur-containing compounds. The amount of sulfur to be reacted with the above-described sulfur compounds will depend upon the percentage of combined sulfur desired in the reaction product. This in turn will be determined by the use for which the product is planned. For example, if the reaction product per se is to be the major lubricant present in a lubricating composition, the reaction product preferably contains less combined sulfur than if it is to be used as an extreme pressure additive in another lubricant base.

When the reaction product is intended for use a a major component in a lubricating composition, sufficient sulfur should be present to give a product having from about to about 30% by weight of combined sulfur. On the other hand, when the reaction product is to be used as an additive to another lubricant, sufficient sulfur should be used to give a product having from about 20 to about 60% by weight of combined sulfur.

It will be noted that the total combined sulfur in the reaction product will be dependent upon is reacted. Hence, it is evident that the less combined sulfur the organic compound originally contains, the more free sulfur it is necessary to react therewith to reach a given combined sulfur content. For example, bis 3-(2-ethylhexoyloxy) propyl sulfide contains about 9% combined sulfur. It is necessary to react this completely with 21% sulfur in order to obtain a reaction product containing about 30% combined sulfur. On the other hand, an adduct of hydrogen sulfide and diallyl ether, having a molecular weight of about 600 and a combined sulfur content of about 22%, requires complete reaction with only about 8% by weight of sulfur in order to obtain a reaction product containing 30% by weight of sulfur.

Preferably, the reaction is carried out under conditions whereby substantially all of the free sulfur originally present in the reaction mixture is reacted with the organic sulfur compound. However, excess sulfur may at times be present in dissolved form in the reaction product, to be used therewith as a modified lubricating composition. Alternatively, free sulfur may be present as an insoluble impurity in the reaction product,

from which it may be separated by selective solvent extraction, centrifuging, filtration, etc.

In carrying out the reaction, the above described organic sulfur compounds are heated with sulfur at temperatures between about C. and

about 250 C., preferably between about 150 C.

and 225 C. The temperature selected for the reaction will depend upon the reactivity of the organic sulfur compound with sulfur, upon the volatility of the organic compound and the reaction product, and upon the apparatus employed.

The apparatus in which the reaction is carried out may comprise a closed system, such as an autoclave, or an open system, preferably equipped with refluxing and/or fractionation means. Alternatively a tubular arrangement may be employed so as to provide for a continuous operation, means being provided for recycling reactants through a reaction zone.

The reaction may take place in either liquid, solution, emulsion or gaseous phases. Hence, it is possible, and frequently even advisable, to use either liquid or gaseous diluents. Liquid diluents may perform several functions, acting as solvents for the monomer and/or the polymer, as solvents for the reaction product, as selective solvents for fractions of the reaction product, as viscosity modifiers, etc.

Both gaseous and liquid diluents are preferably substantially inert toward the other components of the reaction mixture in the temperature range encountered prior to, during and after reaction. The most satisfactory diluents are certain hydrocarbons of either aromatic or aliphatic character. When a diluent is to be used, it is preferably chosen from the group of hydrocarbons boiling between about C. to about 300 C., especially if it is to be used in azeotropic distillation. Hydrocarbons which serve as suitable diluents include the dihydronaphthalenes; cycloheptane, the decanes, including 2-methylnonane and 2,6-dimethyloctane; the octanes, including 2-methyl-3- ethylpentane; the nonanes, such as 2-methyloctane, 2,4-dimethylheptane, 4-ethylheptane. the dodecanes such as di-n-hexyl or 2,4,5,7-tetramethyloctane, etc.

When the reaction is carried out in a closed system, the reaction time required for substantially complete reaction of the organic compound with sulfur usually varies from about one hour to about forty hours. Preferably the other conditions of the reaction are adjusted so as to give a reaction time of 2-8 hours, since this time provides opportunity for close control of the operation without prolonging it unduly. However, if the reaction is carried out in the gaseous phase, or if the organic sulfur compound is reacted with sulfur by bubbling it through a molten sulfur bath, for example, reaction may be substantially instantaneous for a minor fraction of the components, the unreacted portions being recycled for further treatment.

Following the reaction period the product may be purified, if necessary, by removal of sludge, water, unreacted sulfur, unreacted organic compounds, diluents and color. The product so formed may have functional groups, such as hydroxy, carbonyl or carboxyl groups, which are preferably converted to more stable, less reactive derivatives.

Hydrogenation may be employed to reduce carbonyls and improve color. Nickel sulfide, tungsten sulfide and other sulfur resistant catalysts suitable for the reduction of carbonyls may be used.

Either prior to or subsequent to reaction of the organic sulfur compounds with sulfur, other functional groups, especially terminal hydroxyl groups, may be converted, for example, by etherification or esterification into products having more satisfactory stability or improved solubility in mineral oils or synthetic oil lubricants.

Various etherifying agents may be used for etherifying terminal hydroxyls. These include alkyl halides; such as methyl iodide, methyl bromide, ethyl chloride, propyl iodide; aralkyl halides such as benzyl chloride and methylbenzyl chloride; alkoxyalkyl chlorides such as methoxyethyl chloride; carboxyalkylating agents such as sodium 'monochloracetate; and alkylene halides such as allyl chloride. Ordinarily, the etherification is carried out in strongly basic environments; sodium hydroxide, liquid ammonia and quaternary ammonium bases and salts being the usual basic substances present.

Esterification of the terminal hydroxyls may be accomplished with various inorganic groups such as nitrates, phosphates or sulphates. However, preferred esterifying agents are the organic acid anhydrides or acid chlorides, and especially fatty acid anhydrides and their chlorides, including for example, anhydrides or chlorides of formic, acetic, propionic, butyric, hexoic, and 2-ethylhexoic acids, as well as higher fatty acids such as lauric, stearic, myristic, palmitic and capric acids.

At times it is preferable to allow only partial etherification or esterification, thus forming halfethers or half-esters instead of the di-ethers or di-esters sometimes possible. For other purposes the end-group hydroxyls may not only be partially or completely esterified or etherified, but also may be treated so as to result in the formation of mixed ethers, mixed esters or etheresters.

The reaction products of sulfur with the specified types of organic sulfur compounds are effective extreme pressure lubricants by themselves but they are especially suitable as extreme pressure additives for other lubricants, of either mineral oil base or synthetic oil base. Their effect as extreme pressure agents is particularly remarkable in synthetic lubricants having the units of the general configuration ii l: id-91st wherein R is an organic radical, preferably a saturated hydrocarbon radical. Also included are the monomeric and polymeric thioethers having units of the general configuration OR-S--Rr wherein the Rs are organic radicals; monomeric or polymeric polysulfides having units of the general configuration wherein p is an integer and the Rs are organic radicals; and copolymers of individual members of each group with other members of the sams or different groups.

Alkylene oxides, and particularly the alkylene oxides having the oxygen bound to adjacent carbon atoms, form polymers of the above configuration. These monomeric oxides have the general configuration wherein the free valences are satisfied with hydrogens or organic radicals.

Alkylene oxides which form such polymers include ethylene oxide, propylene oxide, 12- butylene oxide, 2,3-butylene oxide, isobutylene oxide, tetramethylethylene oxide, methylphenylethylene oxide, cyclohexene oxide, methylcyclohexene oxid, 1,2-cetene oxide; and other substances containing the epoxide linkage such as epichlorohydrin, epibromohydrin, and glycides such as glycidol and 1,2-epoxybutanol-2, as well as derivatives and polymerizable homologs and analogs of the aforementioned substances.

Copolymers of the alkylene oxides useful in compositions of the present invention include, for example, the copolymers of ethylene oxide and propylene oxide; and copolymers of ethylene oxide and isobutylene oxide; the copolymers of propylene oxide and epichlorohydrin; the copolymers of propylene oxide and 1,2-butylene oxide; the copolymers of propylene oxide and glycidol; and. the copolymers of propylene oxide and isobutylene oxide.

Polymers similar to those above are formed from the alkylene glycols, including the polymethylene glycols, the ethylene glycols, and derivatives thereof. The monomeric and lower polymeric glycols have the general configuration wherein m and n are integers and, the free valences are satisfied with hydrogen atoms or organic radicals. Where n is 1, the general formula is that of an ethylene glycol, or substituted derivative thereof, wherein the glycolic hydroxyls are on adjacent carbon atoms,

Glycols having three carbon atoms separating the glycolic hydroxyls are derived from propane- 1,3-diol (trimethylene glycol) and have the general formula R1 B ink],

wherein n is an integer and R1 and R2 are hydrogen atoms or organic radicals.

If R1 and/or R2 are not hydrogen atoms they may be organic radicals such as alkyl, aralkyl, aryl, etc. Preferably, if they are not hydrogens, they are aliphatic radicals, especially saturated lower aliphatic radicals, but may also be groups which contain olefinic or acetylenic links. Typical of the trimethylene alkyl substituted glycols are the methylated trimethylene glycols, including 1-methylpropane-1,3-diol; 2-methylpropane- 1,3-diol; 1,1-dimethylpropane-1,3-dio1; l,2dimethylpropane-1,3-diol; 1,3-dimethyl propane- 1,3-diol; 2,2-dimethylpropane-1,3-diol; 1,1,2-trimethylpropane-1,3--diol; 1,1,3-trimethylpropane- 1,3-diol; 1,2,2-trimethy1propane-1,3-diol; 1,2,3- trimethylpropane-l,3 diol; 1,1,2,2-tetramethylpropane 1,3 diol; 1,1,3,3-tetramethylpropane- 1,3 diol; 1,2,3,3 tetramethylpropane 1,3-diol;

.etc., radicals, as well as their isomers.

1,1,2,2,3-pentamethylpropane-1,3 diol; 1,1,23,3- pentamethylpropane-1,3-dio1; and hexamethylpropane-1,3-diol.

In place of the methyl groups other alkyl groups may be utilized such as ethyl, propyl, butyl, amyl, hexyl, heptyl, octyl, nonyl, decyl,

Preferably, when alkyl groups are the substituents R1 and R2, they have from 1 to 10 carbon atoms, and still more preferably from 1 to 5.

It will be understood that R1 and R2 may be similar or dissimilar groups. Thus, when expanding the general formula given hereinbefore to its indicated number of carbon atoms, it then becomes 1 l Ho-o-o-o-oH wherein R3 through R8 are either hydrogen atoms or similar or dissimilar organic radicals. Those derivatives of trimethylene glycol, other than trimethylene glycol itself, which give the most satisfactory polymers for general use have either one or two lower alkyl substituents. Thus, 2- methylpropane-1,3-diol and 2,2-dimethylpropane-1,3-diol form excellent polymers when treated according to the method of the present invention.

Other lower alkyl substituted trimethylene glycols which polymerize readily are 1-methyl-2- ethylpropane-1,3-diol; 2-methyl-2-ethylpropane- 1,3 diol; 1 methyl-3-ethylpropane-1,3-diol; 2- methyl-2-propylpropane 1,3-diol; 1-methyl-2- isopropylpropane-1,3-diol; 2-methy1- 2 butylpropane-1,3-dio1; 2-methyl-3-butylpropane-1,3- diol; and the homologs, analogs and derivatives of the same.

One or more of the substituents represented by R3 to Rs in the above general formula may be cycloaliphatic radicals. Thus R3 through Rs may be such radicals as cyclohexyl, methylcyclohexyl, dimethylcyclohexyl, ethylcyclohexy, etc. However, open chain akyl substituents give polymers having preferred properties.

The polymers have modified properties if the trimethylene glycol derivatives contain other active groups, such as additional hydroxyls, carboxyls, carbonyls, halogens, sulfur, etc.

Polymethylene glycols from which the polymeric material of the present invention may be prepared have the general formula R 2 wherein z is an integer, y is an integer greater than 5 and the R substituents attached to the carbons are hydrogen atoms or organic radicals. Preferably a is an integer less than 10, and more preferably is an integer from 1 to 4. Actually, when 2 is more than 1, the glycol is a dimer, trimer, etc., Of the corresponding monomeric glycol. The polymethylene glycols polymerizing most readily are those in which y is an integer from 6 to 20.

Monomeric, unsubstituted polymethylene glycols falling within the above formula include hexane-1,6-diol; heptane-1,7-diol; octane-1,8- diol; nonane-1,9-diol; decane-1,10-diol; dodecane-1,12-diol; and polymerizable homologs, analogs and derivatives of the same.

The above glycols are those in which each R substituent is a hydrogen atom. When one or moreof the-Rs are substituents other than hy- 10 drogen atoms, they may be hydrocarbon radicals, such as aliphatic, aromatic, or alicyclic hydrocarbon radicals, or radicals containing nonhydrocarbon members, such as hydroxyl, carboxyl, or carbonyl groups, or sulfur, selenium, tellurium, phosphorus or nitrogen atoms. Preferably, however, any organic radicals attached to the polymethylene glycol are hydrocarbon radicals. Of these, the aliphatic hydrocarbons are preferred, and the saturated lower aliphatic radicals give the most stable polymers and have the widest utility. Hence, the preferred Rs, other than hydrogen, are the lower alkyls, such as methyl, ethyl, propyl, iso-propyl, butyl, secbutyl, tert-butyl, amyl, iso-amyl, hexyl, etc. groups. Again even when Rs other than hydrogen are present, it is preferred that the monomeric glycol contain a preponderance of hydrogen substituent Rs. The most reactive glycols are those in which less than 4 R's are other than hydrogen, and the greatest reactivity is possessed by those having 2 or less Rs which are organic radicals.

Glycols which fall within the above classification include heptane-1,6-diol; octane-1,6-diol; nonane-1,6-diol; dodecane-1,6-diol; decane-1,6- diol; octane-1,7-diol; nonane-1,7-diol; decane- 1,7-diol; dodecane-1,7-diol; nonane-1,8-diol; decane-1,8-diol; decane-1,9-diol; dodecane-1,9- diol; dodecane-1,10-diol; octane-2,7-diol; nonane-2,7-diol; decane-2,7-diol; dodecane-2,7- diol; nonane-2,8-diol; decane-2,8-diol; dodecane-2,8-diol; decane-2,9-diol; dodecane-2,9-diol; 2,3-dimethylhexane-1,6-diol; 2,4-dimethylhexane-l,6-diol; 2,5-dimethylhexane-1,6-diol; 4,4- diethylhexane-1,6-diol; 5,5-dimethylhexane-1,6- diol; 2-methyl-3-ethylheptane-1,7-diol; 2-ethyl- 3-methylheptane-L'7-diol; 3,3-diethylheptane- 1,7-diol; 3,4-diisopropyloctane-1,8-dio1; etc. and their polymerizable homologs, analogs and derivatives.

The polymers described hereinbefore may be homopolymers or may be copolymers. For example an ethylene glycol may be copolymerized with a trimethylene glycol to give copolymers having units of the general configuration Other copolymers falling within the generalformula of substances improved according to the present invention include the copolymers of an ethylene glycol or a trimethylene glycol with a' polymethylene glycol having more than five carbon atoms separating the glycolic hydroxyls. These copolymers have units of the general conwherein m, n, p and y are integers, and the free valences are satisfied with hydrogen atoms or organic radicals. These include for example, copolymers of ethylene glycol and hexamethylene glycol; trimethylene glycol and hexamethylene glycol, etc.

The alkylene oxides usually are polymerized at temperatures from about 60 C. to about 100 C. in the presence of alkalies, acids, amines or salts. The glycols are polymerized at higher temperatures (150-300 C.) in the presence of dehydration catalysts, such as iodine, mineral acids, such as nitric acid or sulfuric acid, hydrogen halides such as hydrogen iodide or hydrogen chloride; or organic sulfonic acids, such as paratoluene sulfonic acid.

All of the polymers and copolymers described hereinbefore are those having units of the general formula wherein m is an integer greater than 1, and n is 1, thereby giving polymers having units of the general configuration On the other hand, when m is 1 and n is greater than 1, the lubricants have units of the general configuration wherein p in an integer. These substances may be monomeric or polymeric thio-ethers or polysulfides.

The hydroxy thio-ethers and polysulfides which may be reacted with sulfur to form the lubricating compositions of this invention are represented by the general formula HORS- OH J. wherein the Rs are organic radicals especially hydrocarbon radicals or chlorinated hydrocarbon radicals, and p is an integer. When 12 is 1, the general formula is that of a dihydroxy thioether, whereas when p is more than 1 the general formula is that of a dihydroxypolysulfide. Preferably, p is an integer from 1 to 6, and the polymers of greatest utility are those in which p is an integer between 1 and 3, inclusive.

The dihydroxythioethers having the gehieral formula have organic radicals R which are either similar or dissimilar. Preferably for the present purposes they are similar hydrocarbon radicals.

When the ES are saturated aliphatic hydrocarbon radicals, they may beof primary, secondary or tertiary character with relation to the thio-ether sulfur atom, dependent upon their method of formation. For example, the primary dihydroxy thio-ethers have the general formula wherein the Rs are saturated aliphatic radicals. Thio-ethers of this configuration are conveniently prepared by the abnorma addition of terminally unsaturated alcohols with hydrogen sulfide. Thus, when allyl alcohol and hydrogen sulfide are reacted in the presence of ultra-violet light at moderate temperatures, one of the products is bis(gamma-hydroxypropyl) sulfide.

vSuitable alcohols for the preparation of primary dihydroxythioethers include isopropenyl alcohol, allyl alcohol, crotenyl alcohol, methallyl alcohol, and their homologs, analogs and substitution products. Dihydroxy thioethers formed by the above methods include bis(gamma-hydroxyit is preferred that p be a number between 2 and 6, and that the Rs be similar or dissimilar saturated aliphatic hydrocarbon radicals. The latter may have, however, functional groups attached thereto, such as carboxyl, carbonyl, hydroxyl, etc. Preferably, the R's are similar saturated aliphatic radicals having from 2 to 20 carbon atoms. While these latter may be of pri-v mary, secondary or tertiary nature, with respect to the sulfur atom, those forming polymers of the greatest utility have the general formula wherein the Rs are similar saturated aliphatic hydrocarbons having 1 to 19 carbons (preferably 1 to 6) and p is an integer from 2 to 6 (preferably 2 or 3). Such polysulfides may be prepared, for example, by the condensation of two molecules of a mercaptoalkyl alcohol.

The various synthetic lubricants described above may have one or more terminal hydroxyls which may be converted to less active radicals,

by such operations as etherification or esterification, as described hereinbefore.

The present reaction products may be empolyed as extreme pressure agents in either mineral oils, in the synthetic lubricants described above, or in other synthetic lubricants and lubricating compositions. In some cases it is necessary to use a solvent for the compound or to form colloidal suspensions of the compound in the major lubricant. While some of these reaction products have only limited solubility in hydrocarbon oils, it is to be remembered that, because of their efiiciency, amounts as low as 0.05% by weight may be used, although proportions of 5% by weight or higher may be necessary for certain purposes. Peptizing agents as well as mutual solvents may be used, if necessary, in order to maintain a suitably homogeneous composition.

Many of the more diflicultly soluble materials are rendered more soluble by the introduction of alkyl groups, particularly those containing four or more carbon atoms. The isoamyl, 2-ethyl hexyl, octyl, lauryl and octadecyl radicals substantially increase the solubility of organic compounds in oil. One or more of such groups may be introduced as required.

It is sometimes advantaegous to start with a mixture of organic sulfur compounds or to combine individual reaction products of the hereindescribed process in order to obtain composite asoama.

properties having special properties. Furthermore other agents may be present in the lubricating compositions. For instance, pour point dopressors, other .extreme pressure agents, oxidation inhibitors, viscosity index improvers, etc. may be employed.

Organic acids, especially water-insoluble acids which are capable of forming water-insoluble metallic soaps are highly effective corrosion inhibitors when used in the compositions of the present invention, especially if the lubricant base is of the class of synthetic lubricants described hereinbefore.

Oxidation inhibitors which are especially effective in the compositions of the present invention, especially when the lubricant base is a synthetic oil of the character described above, include monocyclic amino phenols, polycyclic diamines, substituted monocyclic amines and 1,2-dihydroxybenzene.

The compositions of the present invention are eminently suitable for use as automotive crankcase lubricants, Diesel engine lubricants, cutting oils, rolling oils, hypoid gear lubricants and greases. Greases should contain graphite or gelling agents such as metallic soaps, etc.

Having described the preparation, properties and uses of the reaction products defined above, the following examples are presented as specific embodiments of the invention.

Example 1 Fifteen mols diallyl ether, 15 mols hydrogen sulfide and mol per cent di-tertiary-butyl peroxide were heated together in an autoclave at 100 C. for 30 hours. The water-white, oily re-- action product was subjected to distillation, the

fraction (70% of the product) distilling above.

240 C. at 0.2 cm. mercury pressure being used for reaction with sulfur.

Eighty parts by weight of the adduct so prepared was heated with twenty parts by weight of flowers of sulfur at 180-190 C. for 3 hours. The product was used without modification or purification in the following test. It contained 35.3% combined sulfur, less than 0.1% free sulfur as determined by potentiometie determination, had a viscosity index of 125, and a pour point of 0 F. i

A polymer of propylene oxide having a molecular weight of about 600 was tested for extreme pressure characteristics both alone and in the presence of the reaction product prepared as described in the preceding paragraphs. The test was carried out with the 4-ball apparatus described by Boelage in Engineering, July 14, 1933. In this apparatus, the wear of the balls as well as the pressure causing welding can be determined. The following results were obtained:

Scar Diameters, mm.

Rample 1 2 3 Weight per cent reaction product in polymeric lubricant Loag6 kilograms:

1 After one minute at 1500 R. P. M.

Example 2 Five parts of the reaction product of sulfur and the adduct of diallyl ether and hydrogen sulfide, prepared as described in Example 1, was dissolved in parts dioctyl phthalate. The composition was tested for extreme pressure properties in the 4-ba1l machine described above. For comparison, unmodified dioctyl phthalate also was tested. The data obtained are given in the table below:

Scar Diameters, mm.

Same, con- Unmodified taining 5% Dioctyl Sulfur Re- Phthalate action Product wherein R1 is an unsaturated aliphatic hydrocarbon radical, each R is a divalent aliphatic hydrocarbon radical and n is an integer.

2. A composition of matter consisting essentially of a major amount of a propylene oxide polymer and 3-5% by weight of the sulfurized reaction product according to claim 1.

3. A composition of matter consisting essentially of a major amount of dioctyl phthalate and 5% by weight of the sulfurized reaction product according to claim 1.

4. A composition of matter consisting essentially of a major amount of an alkylene oxide polymer and 35 percent by weight of the sulfurized reaction product according to claim 1.

5. As a new composition of matter the sulfurized reaction product obtained by heating 10 to 60 par-ts by weight of sulfur with a suiiicient amount of a polyether so that the total of sulfur and polyether is 100 parts by weight at a temperature between 100 and 250 C. for a time between 1 and 40 hours, said polyether boiling above 240 F. at 0.2 cm. mercury pressure and havin the general formula wherein n is an integer.

6. As a new composition of matter the sulfurized reaction product obtained by heating 10 to 60 parts by weight of sulfur with a suificient amount of a polyether so that the total of sulfur and polyether is 100 parts by weight at a. temperature between 100 and 250 C. for a time between 1 and 40 hours, said polyether boiling above 240 15 F. at 0.2 cm. mercury pressure and having the UNITED STATES PATENTS general formula Number Name Date CHz=CHz(OCzH4SC2H4)nOCzH4SH 3 ,6 5 01in Apr. 8, 1941 whereinnis anmbeger 5 2,237,627 01in Apr- 1 4 7. A composition of matter consisting essengiggz g fi' tially of a major amount of a. lubricant of the 2326483 Moran Aug 1943 group consisting of an alkylene oxide polymer 213981179 Vaughn 16"1946 and dioctyl phthalaite and 3-5% by weight of the 2 409687 Rogers Oct 1946 sulfurized reaction product according to claim 1. 10 2415002 Bruson i 1947 DENHAM HARMAN' 2,484,369 Ballard oct. 11, 1949 GEORGE L. PERRY.

REFERENCES CITED The following references are of record in the 15 Certificate of Correction Patent No. 2,562,144 July 24, 1951 DENHAM HARMAN ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 14, line 32, after amount of insert the letter a;

and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Oflice.

Signed and sealed this 22nd day of January, A. D. 1952.

THOMAS F. MURPHY,

Assistant Commissioner of Patents. 

1. AS A NEW COMPOSITION OF MATTER THE SULFURIZED REACTION PRODUCT OBTAINED BY HEATING 10 TO 60 PARTS BY WEIGHT OF SULFUR WITH A SUFFICIENT AMOUNT OF POLYETHER SO THAT THE TOTAL OF SULFUR AND POLYETHER IS 100 PARTS BY WEIGHT AT A TEMPERATURE BETWEEN 100 AND 250* C. FOR A TIME BETWEEN 1 AND 40 HOURS, SAID POLYETHER BOILING ABOVE 240* F. AT 0.2 CM. MERCURY PRESSURE AND HAVING THE GENERAL FORMULA 